1. Field of the Invention
The present invention relates to a particle material for anisotropic conductive connection, and to a method for manufacturing the same.
2. Description of the Related Art
The connection terminals of semiconductors are routinely connected to the connection terminals of the mounting substrates thereof by anisotropic conductive connection. In this anisotropic conductive connection, an anisotropic conductive connection material in the form of a film or paste, comprising fine conductive particles dispersed in an insulating adhesive agent, is sandwiched between materials to be connected, and this assembly is heated and pressed to bond and electrically connect the two materials.
Recently we have seen the patterns of the connection terminals subjected to anisotropic conductive connection become finer and finer, which raises the concern that shorts might occur during anisotropic conductive connection. Consequently, conductive particles covered with a thin thermoplastic resin layer or thermosetting resin layer have come to be used as the conductive particles for anisotropic conductive connection.
Unfortunately, when conductive particles are covered with a thermoplastic resin, the thermoplastic resin film sometimes comes off depending on the solvent used in the manufacture of the anisotropic conductive connection material, and this limits which solvents and which compositional blends can be used. Furthermore, shorting between adjacent patterns caused by the heating and pressing involved in anisotropic conductive connection can no longer be ignored. Also, since the proportion of thermoplastic resin increases when the amount of conductive particles contained in the anisotropic conductive connection material is increased, another problem is lower heat resistance of the anisotropic conductive connection material. Finally, as the spacing narrows between bumps to be connected, the conductive particles tend to aggolomerate due to the softening of the thermoplastic resin on the surface of the conductive particles, resulting in inferior insulation characteristics (that is, how well insulation is maintained between patterns to be insulated).
Meanwhile, the problems encountered in the use of conductive particles covered with a thermoplastic resin do not occur in the case of conductive particles covered with a thermosetting resin, but another problem occurs such that high pressing force is required to break up the insulating cover film of the conductive particles during anisotropic conductive connection, which damages the materials being connected.
The present invention was conceived in an effort to solve the above problems encountered with prior art, and it is an object thereof to provide a particle material in which the drawbacks to conventional conductive particles for anisotropic conductive connection that are covered with a thermoplastic resin or thermosetting resin are improved, as well as a method for manufacturing these conductive particles.
The inventors perfected the present invention upon discovering that the stated object could be achieved by using an insulating gelled resin with a gel proportion of at least 90% as the insulating resin that covers the conductive particles.
Specifically, the present invention provides a particle material for anisotropic conductive connection, comprising a conductive particle and an insulating resin layer covering the surface thereof, wherein the insulating resin layer is composed of an insulating gelled resin with a gel proportion of at least 90%.
The present invention also provides a method for manufacturing a particle material for anisotropic conductive connection, the particle material comprising a conductive particle and an insulating resin layer covering the surface thereof, wherein the method comprises fixing an insulating gelled resin powder with a gel proportion of at least 90% to the surface of a conductive particle by a physical/mechanical method to form the insulating resin layer.